Ionis and Otsuka's RNA therapy Ulefnersen shows functional and survival gains in rare FUS-ALS in Phase 3 trial

Ionis Pharmaceuticals and Otsuka Pharmaceutical reported that their antisense oligonucleotide drug Ulefnersen improved both functional impairment scores and overall survival in a Phase 3 study of patients with a rare, genetic form of ALS caused by FUS mutations.

The trial enrolled 73 participants and met its primary endpoint, showing a statistically significant benefit compared with placebo on the key functional and survival measures.

Investors and clinicians noted that Ulefnersen is the first therapy to demonstrate a clear advantage in a placebo‑controlled trial for FUS‑ALS. The companies said they will meet with the FDA and other regulators to explore pathways for expedited approval.